Is there abnormal noise from the rolling bearings of the motor? Troubleshooting and handling methods

Electric motors are crucial transmission components in industrial production and equipment operation. As a core transmission part of the motor, ball bearings can cause significant disruptions if they produce abnormal noises. This can affect equipment efficiency, potentially leading to downtime and unnecessary losses and waste. Whether you're using internationally renowned brands like Bearing Timken, precision bearings like Nachi Bearing, or high-temperature bearings and mini bearings designed for special applications, understanding how to troubleshoot and resolve abnormal noises is key to ensuring stable equipment operation.

Below, our BLH bearing engineers have compiled a list of common abnormal noise issues related to motor rolling bearings, along with practical solutions to help you quickly resolve these pain points.

When the motor is running, a screwdriver is all you need for a preliminary diagnosis-place the tip of the screwdriver against the bearing dust cover and listen closely with your ear to the screwdriver handle:

• Normal condition: If a faint rolling sound can be heard between the inner and outer rings, the sound is monotonous, uniform, and without any extraneous noises, it indicates that the bearing is in good condition (this characteristic should be observed during normal operation for both the smooth transmission of insert ball bearings and the quiet advantage of rubber bearings).

• Abnormal alarm: If a harsh, chaotic, or regular abnormal noise occurs, please stop the machine immediately for inspection to prevent the fault from escalating and causing damage to the motor.

Solutions:

① Disassemble the motor and inspect the wear of the inner and outer rings and rolling elements of the rolling bearing. If the wear exceeds the standard, replace the bearing with the same model (if the original machine uses international brands such as Bearing Timken or SKF bearings, it is recommended to choose the same compatible model from the BLH brand, as BLH bearings are compatible with models from major international brands, offer consistent quality, and are much cheaper);

② If the abnormal clearance is caused by deformation of the bearing support or bearing housing, the support and bearing housing must be replaced simultaneously to prevent further damage to the new bearing.

Possible cause: The rolling bearing lubricating grease is too dirty, with impurities intruding (even with insert ball bearings that have good dustproof performance, impurities can still enter due to seal aging during long-term high-temperature operation).

Solution:
① Thoroughly clean the bearing with kerosene or a bearing cleaner (note that precision components such as jewelry bearings require a special cleaning agent to avoid corrosion);

② Replace with new lubricating grease. The grease type must match the bearing type-for example, high-temperature bearings require high-temperature resistant grease, while mini bearings require a low-viscosity, easily penetrating special grease. Do not mix greases, and pay attention to the amount of bearing grease applied.

Possible cause: A single rolling element in the bearing is broken (commonly caused by uneven stress during installation or the use of inferior bearings; while the probability is low with high-quality Nachi and BLH bearings, proper installation is still crucial).

Solution:
① Immediately stop the machine and replace the bearing to prevent the broken steel ball from scratching the inner and outer raceways, rendering the entire bearing assembly unusable;
② During replacement, check the bearing support and bearing housing for deformation. If the bearing support is jamming the rolling elements, it must be repaired or replaced simultaneously.

Possible causes: Insufficient bearing grease, or incorrect grease type (e.g., using ordinary grease on a high-temperature bearing, causing grease failure at high temperatures; or using high-viscosity grease on mini bearings, which cannot penetrate and lubricate).

Solutions:

① Add new grease, the amount of which should be controlled to 1/3-2/3 of the bearing housing volume (too much grease can cause overheating, too little will result in insufficient lubrication);

② If the grease type is incorrect, thoroughly clean the bearing and replace it with a suitable grease – for example, rubber bearings require a special grease that does not corrode rubber to prevent seal aging. For more bearing grease types, please consult BLH Bearing Factory. We will provide you with one-stop bearing solutions.

Possible cause: Improper fit between the bearing inner ring and the shaft, or between the outer ring and the bearing support (too loose will cause relative sliding, too tight will cause the bearing to squeeze and produce abnormal noise, commonly seen in insertion ball bearing installation misalignment and bearing tolerance).

Solution:

① Measure the fit tolerance between the hardware spindle and the bearing inner ring. If too loose, replace with a bearing with a larger interference fit; if too tight, grind the hardware spindle (pay attention to precision control to avoid affecting the fit of related components such as the conrod bearing);

② Check the fit clearance between the bearing support and the bearing housing and the outer ring. If the support is deformed, it needs to be recalibrated or replaced.

Possible causes: Misaligned bearing installation (e.g., high-temperature bearings not aligned with the shaft shoulder during installation, or uneven stress on precision bearings like jewelry bearings), or improper assembly of the bearing support and end cap can all cause bearing overheating and abnormal noise.

Solutions:

① Remove the bearing dust cover. Use a copper rod to press against the inner ring of the bearing and tap it symmetrically with a hammer to ensure the bearing is properly seated on the shaft shoulder.

② Reassemble the end caps, adjust the bearing support position, ensuring a good fit between the end caps and the machine base stop. Tighten the bolts diagonally to avoid uneven stress and ensure the bearing and shaft are concentric.

1. Correctly select the bearing model: Choose the appropriate model based on the motor's operating conditions-high-temperature bearings are preferred for high-temperature environments, mini bearings or high-precision bearings are selected for precision instruments, and BLH bearings of the same quality as Bearing Timken and Nachi bearings are considered for high-load transmissions.

2. Regular inspection and maintenance: Regardless of the type of rolling bearing, the lubricating grease must be inspected or replaced according to the service life (rubber bearings should also have their seals checked for aging, and the dust cover of insert ball bearings should be cleaned of impurities) to avoid malfunctions caused by neglected maintenance.

3. Correct bearing installation specifications: Strictly follow the tolerance requirements of the drawings when assembling bearings, especially for components with high precision requirements such as conrod bearings and high-temperature bearings, to avoid hidden damage caused by rough handling during installation.

No matter where you are in the world, BLH Bearings can quickly respond to and resolve any abnormal noises from your motor's rolling bearings, minimizing downtime losses. If you have any questions about bearing selection (such as matching bearing units) or maintenance, please feel free to contact BLH Bearings. Our engineers will provide one-on-one service, and the BLH Bearings factory will offer targeted solutions to help ensure stable equipment operation!

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